1. Field of the Invention
This invention relates to tape cartridges for digital recording, such as digital data service (DDS) and digital audio tape (DAT), and other applications, and more particularly to tape cartridges of the type having brakes for hubs around which a tape is wound.
2. Prior Art
Tape cartridges in common use comprise housing made up of upper and lower half casings, a pair of hubs around which a length of tape is wound and which are turnably supported within the housing, said lower half casing having a pair of holes through which drive shafts of a recorder/reproducer are inserted to drive the hubs, a slider which slidably covers and uncovers the holes, said slider being disposed along the outer surface of the lower casing, and a hub brake having brake pawls adapted to be engaged with and disengaged from teeth provided around the hubs, said hub brake being disposed slidably within the cartridge housing. The hub brake slides to release its pawls out of engagement with the teeth, in an interlocked operation, when the front lid that covers the tape portion pulled out to the front of the upper and lower casings of the housing is turned open.
For example, Japanese Utility Model Application Kokoku No. 2-49031 discloses a cartridge housing made up of an upper half casing 1 and a lower half casing 2 as illustrated in FIG. 5, wherein a pair of hubs 3 around which a length of tape 4 is wound are turnably supported, said lower casing having a pair of holes through which driving shafts of a recorder/reproducer to drive the hubs 3 are to be inserted, a slider 7 which slidably covers or uncovers the holes is disposed along the outer surface of the lower casing 2, and a hub brake 8 is provided inside the cartridge so as to slide along the inner surface of the upper casing 1, said hub brake having brake pawls 81 adapted to engage teeth 31 formed around the hubs 3, in such manner that the pawls 81 of the hub brake 8 are released against the urging of a spring 9 as the brake is caused to slide in an interlocked operation with the opening of an openable front lid 10 which covers a portion of the tape 4 pulled out to the front of the housing.
The hub brake 8, with both ends bent at right angles, can slide along the both inner end surfaces of the upper and lower half casings 1, 2.
Tape cartridges of the type described above are in use for recording audio-frequency signals and data in general. Recent demand for larger and larger memory capacities for data storage has been met by reducing the thickness of tape or increasing the diameter of the tape wound up in a roll.
When such a cartridge is used, the tape roll is unwound to force an expose portion of it ahead at the front of the cartridge. With a large tape roll, it can occur that the tape portion being unwound from the roll is damaged by sliding contact with the inner surface of the hub brake.
This will be more fully explained below. Referring to FIG. 5, the hub brake 8 has a pair of connecting plate parts 83 at the left and right ends with which the brake can move back and forth along the inner walls of the upper and lower casings. The connecting plate parts 83 in turn have arms with projections 85 formed at their front ends, respectively. The hub brake 8 is activated as part of the front lid 10 presses the projections 85 when the lid is turned open and closed. In the arrangement described, the tape 4 that is partly pulled out to the front of the housing can sometimes come in contact with part of the connecting plate parts 83 of the hub brake 8 and be damaged by the sliding contact.
The present invention solves the above problem in the following way. The invention provides an improvement of a tape cartridge which comprises a housing made up of upper and lower half casings, a pair of hubs around which a length of tape is wound and which are turnably supported within the housing, a freely openable front lid provided at the front of the housing to cover an exposed portion of the tape, and a hub brake having a pair of brake pawls adapted to be engaged with and disengaged from teeth provided around the hubs, said hub brake being disposed along the inner wall surface of the upper casing within the cartridge housing and normally urged toward the hubs by an elastic member. The invention is characterized in that the hub brake comprises a main face plate part having the brake pawls, connecting plate parts perpendicularly bent and extended downwardly from the left and right ends of the main face plate part, arms extending frontwardly from the lower ends of the connecting plate parts, and projections adapted to be engaged with part of the front lid when the lid is turned open, to force the arms frontwardly, said connecting plate parts having recesses, one for each, formed in the rear inner portions thereof facing the exposed tape portion.
The recesses formed in the rear inner portions of the connecting plate parts are preferably bevels tapering rearwardly and outwardly, but they may take the form of steps instead.